a. Field of the Invention
The present invention relates to wheelchair seats and, in particular, to a wheelchair seat with a back that can be tilted relative to the bottom of the seat.
b. Prior Art
A typical wheelchair seat has a bottom portion on which the patient sits, and a back portion against which the patient's back rests. The back and bottom portions are typically fixed at a particular angle relative to one another. Wheelchair designs exist that permit the back and bottom portions to be reclined together, without changing the relative angle between the two. That is, when the back portion is rotated backwardly, the bottom portion rotates upwardly.
In some situations such as particular therapies, however, it is preferable to recline the patient's back without changing the angle of the seat bottom. U.S. Pat. No. 4,333,681 to Nelson discloses a wheelchair with a seat back that is controlled with an electric ram. The electric ram has a rod that extends and contracts to recline the wheelchair seat back. The Nelson arrangement requires an electric power source to operate.
U.S. Pat. No. 3,712,671 to Dalton discloses a wheelchair seat back that is pivotally mounted to a hinge pin. The seat back travels along a support, and the seat back may be locked into place along the support by tightening a wing nut. The support extends a substantial distance behind the seat back, and physically extends into the space that the person pushing the wheelchair is likely to occupy.
U.S. Pat. No. 2,165,529 discloses a wheelchair with an adjustable back to which is attached an adjustable ratchet bar. The ratchet bar has a number of detents that are engageable with a stop. The seat back can be reclined backwardly, and the position fixed in place by engaging a detent with the stop. The detents are jagged, however, and present a rough surface onto which the user's clothing can catch.